Use Windows Explorer to browse to C:\Program Files. If it exists, delete the Ability Office 4 folder (use right-click/Delete).

Check the Start/Programs menu - if Ability Office remains, use the right-click menu to delete.

Run setup.exe to start install (use Windows explorer and browse to the folder you unzipped to and double click setup.exe)

Advanced - remove Ability from the registry

Note: this step is not usually necessary. Only follow these instructions if you are an experienced user and/or you have been explicitly instructed by Ability technical support to do so.

On uninstall, your system registry should be updated to remove relevent Ability entries. It's possible (usually because of multiple
installations) that this does not happen. To remove Ability from the registry, please carefully follow these steps. The best
time to do this would be after step 3 above, but you can also do it after Ability is installed (in which case, the Ability
registry entries will be re-built when each application is first run).

Select Start/Run and enter REGEDIT

Browse (opening the [+] by the entries) to:
HKEY_CURRENT_USER\Software

Delete the Ability 4.0 entry by right-clicking over it and selecting Delete.